ABSTRACT A growing human health concern is that exposure to chemicals in our environment harms the highly vulnerable period of human brain development. Indeed, increasing evidence shows that even simple, acute exposures of the developing brain to select agents cause profound neurological disorders such as epilepsy, autism and intellectual disability. Despite this vulnerability, the reliable, high-throughput identification of neurotoxins that affect this process has been lagging. Major hurdles include the time and cost required for these assays when using animal models, the difficulty of relating rodent data to human brain development, and the difficulty in generating easy-to-interpret metrics for how a chemical affects the multiple cell types required for proper neurodevelopment. Nzumbe Inc. received a Phase I grant to address these challenges. Our work established and validated a 96- well, high-content assay that determines whether a chemical affects neural differentiation. We identified discrete timepoints and cell-specific markers that can be used to screen for aberrant changes in neural differentiation following exposures to chemicals. We are now seeking Phase II SBIR funding in response to RFA-ES-17-007 ?Novel Assays for Screening the Effects of Chemical Toxicants on Cell Differentiation?. Our plans under Phase II are to further innovate and deliver a more rapid, predictive test, called NeuroPredictTM, which would greatly reduce cost and give simple, easy-to-interpret metrics to determine how a chemical affects neural differentiation. Our first Aim is to create specially engineered human iPSC-derived neural progenitor cells (hNPCs) that express reporter proteins that identify the basic cell types that arise during neural differentiation. These reporter proteins can be assayed at multiple time points during the differentiation process. The ratio of these different reporter proteins will represent the relative proportion of the basic cells type present during neural differentiation (hNPC, glial cells, and neurons). Thus, a toxic effect of chemical exposure on the differentiation process will be reflected by changes in the reporter protein outputs. The second Aim is to use the NeuroPredictTM assay to classify the early functional and disease-associated effects of known neurotoxins on neural differentiation. This strategy will provide data for a short-term assay that can quickly classify chemicals with unknown neurotoxic effects.